Process for preparation of esculetin compounds, esculetin compounds and intermediates thereof, and use of both

ABSTRACT

An esculetin compound, an intermediate thereof, a process for manufacturing an esculetin compound, and an antifungal composition for agriculture and horticulture and an herbicide comprising an esculetin compound or an intermediate thereof are provided. The process for manufacturing an esculetin compound is a low-cost, high-yield, and industrially practicable process, and comprises the following step.  
     A process for manufacturing an esculetin compound of the formula (2):  
                 
 
     characterized by cyclizing a trihydroxybenzaldehyde compound of the formula (1):  
                 
 
     in an aprotic polar solvent in the presence of a weak base, with acetic anhydride or the like.

TECHNICAL FIELD

[0001] The present invention relates to an esculetin compound, anintermediate thereof, a process for manufacturing an esculetin compound,and an antifungal composition for agriculture and horticulture and anherbicide comprising an esculetin compound or an intermediate thereof,particularly a novel process for manufacturing an esculetin compoundhaving an activity. Esculetin compounds are now important compounds inthe pharmaceutical industry, and useful as a synthetic intermediate inthe chemical industry.

BACKGROUND ART

[0002] Esculetin is a compound in which hydrogen atoms at 6- and7-positions of coumarin are substituted with hydroxyl groups, i.e.,6,7-dihydroxycoumarin. Many methods for manufacturing coumarins areknown, but there are few reports of a method of manufacturing esculetinshaving hydroxyl groups at 6- and 7-positions.

[0003] As a method for manufacturing esculetin per se, a method forpreparation by hydrolyzing natural esculin (i.e.,6,7-dihydroxycoumarin-6-glucoside) by an acid [Merz, Arch. Pharm., vol.270, 486(1932)], or a method by reacting 1,2,4-triacetoxybenzene withmalic acid in sulfuric acid [Bull. Soc. Chim. France 512(1947),Heterocycle, vol. 41, 1979(1995)] is known.

[0004] However, the method for hydrolyzing natural esculetin is limitedin an amount supplied. Further, the method for synthesizing high-purityesculetin using 1,2,4-triacetoxybenzene and malic acid is industriallydisadvantageous in view of a low yield (18%) and the use of 98% sulfuricacid.

[0005] As a method for manufacturing esculetin, a method for preparingesculetin by synthesizing esculetin having one or more substituents, andthen by removing the substituents is known. In the method,2-hydroxy-4,5-dimethoxybenzaldehyde is reacted with malonic acid inpyridine in the presence of aniline to synthesize scoparone-3-carboxylicacid, the carboxyl group at 3-position is decarboxylated, and methylether is broken with hydriodic acid to synthesize esculetin[Phytochemistry, 27, 391(1988)]. As a method for synthesizing anesculetin derivative, a method for synthesizing scoparone by reacting anorthohydroxybenzaldehyde derivative with carbethoxymethylenetriphenylphosphorane [Indian J. Chem., vol. 21B, 759(1982)], a methodfor synthesizing a coumarin derivative by reacting a salicylaldehydederivative with carbethoxymethylene triphenylphosphorane [Chem. Pharm.Bull. vol. 40, 2614(1992)], a method for synthesizing a coumarinderivative by reacting a salicylaldehyde derivative with aceticanhydride and sodium acetate [Chem. Pharm. Bull. vol. 40, 2614(1992),Chem. Ber. vol. 32, 287(1899)], a method for synthesizing scoparone(6,7-dimethoxycoumarin) by reacting 2-hydroxy-4,5-dimethoxy-benzaldehydewith acetic anhydride and potassium acetate in the presence ofhydroquinone [Japanese Unexamined Patent Publication (Kokai) No.48-22466], or the like is known. The above methods are a method forsynthesizing an esculetin derivative, but not a method for directlysynthesizing esculetin per se. Therefore, a step of removing aprotecting group or a substituent is necessary, and thus the yieldbecomes low.

[0006] In the above method for synthesizing6-isopropoxy-7-methoxycoumarin by reacting a salicylaldehyde derivativewith acetic anhydride and sodium acetate, the above reference disclosesthat the yield is 45.7%, which is not enough. Further, the yield of theabove method for synthesizing scoparone by reacting2-hydroxy-4,5-dimethoxy-benzaldehyde with acetic anhydride and potassiumacetate in the presence of hydroquinone is 41%, which is not enough.

[0007] The present inventors have conducted intensive studies of amethod for manufacturing an esculetin compound which can satisfyindustrial requirements and, as a result, found that an esculetincompound can be obtained with a high yield, by cyclocondensing aspecific benzaldehyde compound in an aprotic polar solvent (such asN,N-dimethylformamide or the like) in the presence of a weak base (suchas sodium acetate or the like), with acetic anhydride or the like.Further, the present inventors found that novel compounds are includedin starting materials, intermediate products, and products used in theabove novel manufacturing method found by the present inventors.Furthermore, the present inventors found that compounds having anantifungal activity or an herbicidal activity are included in theintermediate products.

[0008] The present invention is based on the above findings.

DISCLOSURE OF INVENTION

[0009] Accordingly, the present invention relates to a process formanufacturing an esculetin compound of the general formula (2):

[0010] wherein R¹ and R² are, independently, a hydrogen atom, an alkylgroup having 1 to 5 carbon atoms, an optionally substituted benzylgroup, a formyl group, or an optionally substituted alkyl-carbonyl groupin which the alkyl moiety has 1 to 4 carbon atoms, or R¹ and R² togetherform a —CH₂— group or a —C(CH₃)₂— group; characterized bycyclocondensing a trihydroxybenzaldehyde compound of the general formula(1):

[0011] wherein R¹ and R² have the same meanings as above; and R³ is ahydrogen atom, a formyl group, or an optionally substitutedalkyl-carbonyl group in which the alkyl moiety has 1 to 4 carbon atoms;in an aprotic polar solvent in the presence of a weak base, with aceticanhydride or a compound which forms acetic anhydride in the reactionsystem.

[0012] The present invention relates to a process for manufacturing atrihydroxybenzaldehyde compound of the general formula (1),characterized by performing a formylation of a trihydroxybenzenecompound of the general formula (3):

[0013] wherein R¹ and R² are, independently, a hydrogen atom, an alkylgroup having 1 to 5 carbon atoms, an optionally substituted benzylgroup, a formyl group, or an optionally substituted alkyl-carbonyl groupin which the alkyl moiety has 1 to 4 carbon atoms, or R¹ and R² togetherform a —CH₂— group or a —C(CH₃)₂— group; and R³ is a hydrogen atom, aformyl group, or an optionally substituted alkyl-carbonyl group, inwhich the alkyl moiety has 1 to 4 carbon atoms.

[0014] As the trihydroxybenzaldehyde compound of the general formula(1), a trihydroxybenzaldehyde compound of the general formula (1)wherein R¹ and R² are, independently, a hydrogen atom, an alkyl grouphaving 1 to 5 carbon atoms, a benzyl group, or an acetyl group, or R¹and R² together form a —CH₂— group or a —C(CH₃)₂— group, and R³ is ahydrogen atom or an acetyl group is preferable.

[0015] As the esculetin compound of the general formula (2), anesculetin compound of the general formula (2) wherein R¹ and R² are,independently, a hydrogen atom, an alkyl group having 1 to 5 carbonatoms, a benzyl group, or an acetyl group, or R¹ and R² together form a—CH₂— group or a —C(CH₃)₂— group, and R³ is a hydrogen atom or an acetylgroup is preferable.

[0016] As the trihydroxybenzene compound of the general formula (3), atrihydroxybenzene compound of the general formula (3) wherein R¹ and R²are, independently, a hydrogen atom, an alkyl group having 1 to 5 carbonatoms, a benzyl group, or an acetyl group, or R¹ and R² together form a—CH₂— group or a —C(CH₃)₂— group, and R³ is a hydrogen atom or an acetylgroup is preferable.

[0017] The present invention relates to a trihydroxybenzaldehydecompound of the general formula (10):

[0018] wherein R¹¹ and R¹² are, independently, a hydrogen atom or analkyl group having 2 to 5 carbon atoms, or R¹¹ and R¹² together form a—C(CH₃)₂— group; and R¹³ is a hydrogen atom, a formyl group, or anoptionally substituted alkyl-carbonyl group in which the alkyl moietyhas 1 to 4 carbon atoms; with the proviso that R¹¹ and R¹² are not ahydrogen atom at the same time.

[0019] As the trihydroxybenzaldehyde compound of the general formula(10), a trihydroxybenzaldehyde compound of the general formula (10)wherein R¹¹ and R¹² are, independently, a hydrogen atom or an alkylgroup having 2 to 5 carbon atoms, or R¹¹ and R¹² together form a—C(CH₃)₂— group, and R¹³ is a hydrogen atom or an acetyl group, with theproviso that R¹¹ and R¹² are not a hydrogen atom at the same time, ispreferable.

[0020] The present invention relates to an esculetin compound of thegeneral formula (20):

[0021] wherein R²¹ and R²² are, independently, a hydrogen atom, an alkylgroup having 2 to 5 carbon atoms, an optionally substituted benzylgroup, a formyl group, or an optionally substituted alkyl-carbonyl groupin which the alkyl moiety has 1 to 4 carbon atoms, or R²¹ and R²²together form a —C(CH₃)₂— group, with the proviso that R²¹ and R²² arenot a hydrogen atom at the same time, and that R²¹ and R²² are not aformyl group, or an optionally substituted alkyl-carbonyl group in whichthe alkyl moiety has 1 to 4 carbon atoms at the same time.

[0022] As the esculetin compound of the general formula (20), anesculetin compound of the general formula (20) wherein R²¹ and R²² are,independently, a hydrogen atom, an alkyl group having 2 to 5 carbonatoms, a benzyl group, or an acetyl group, or R²¹ and R²² together forma —C(CH₃)₂— group, with the proviso that R²¹ and R²² are not a hydrogenatom at the same time, and that R²¹ and R²² are not an acetyl group atthe same time is preferable.

[0023] The present invention relates to a trihydroxybenzene compound ofthe general formula (30):

[0024] wherein R³¹ is an optionally substituted benzyl group, R³² is ahydrogen atom, a formyl group, or an optionally substitutedalkyl-carbonyl group in which the alkyl moiety has 1 to 4 carbon atoms,or R³¹ and R³² together form a —C(CH₃)₂— group; and R³³ is a hydrogenatom, a formyl group, or an optionally substituted alkyl-carbonyl group,in which the alkyl moiety has 1 to 4 carbon atoms.

[0025] As the trihydroxybenzene compound of the general formula (30), atrihydroxybenzene compound of the general formula (30) wherein R³¹ is abenzyl group, R³² is a hydrogen atom or an acetyl group, or R³¹ and R³²together form a —C(CH₃)₂— group, and R³³ is a hydrogen atom or an acetylgroup is preferable.

[0026] The present invention relates to an antifungal composition foragriculture and horticulture, characterized by comprising, as an activeingredient, the trihydroxybenzaldehyde compound of the general formula(10), the esculetin compound of the general formula (20), or thetrihydroxybenzene compound of the general formula (30).

[0027] The present invention relates to an herbicide, characterized bycomprising, as an active ingredient, the trihydroxybenzaldehyde compoundof the general formula (10), the esculetin compound of the generalformula (20), or the trihydroxybenzene compound of the general formula(30)

BEST MODE FOR CARRYING OUT THE INVENTION

[0028] In the process of the present invention for manufacturing anesculetin compound, the trihydroxybenzaldehyde compound of the generalformula (1) is used as a starting material.

[0029] In the general formula (1), R¹ and R² may be the same ordifferent, and R¹ and R² are, independently, a hydrogen atom, an alkylgroup having 1 to 5 carbon atoms, an optionally substituted benzylgroup, a formyl group, or an optionally substituted alkyl-carbonyl groupin which the alkyl moiety has 1 to 4 carbon atoms, or R¹ and R² togetherform a —CH₂— group or a —C(CH₃)₂— group, and R³ is a hydrogen atom, aformyl group, or an optionally substituted alkyl-carbonyl group in whichthe alkyl moiety has 1 to 4 carbon atoms.

[0030] The term “alkyl group” as used herein means a straight-chainalkyl group, a branched alkyl group, or a cyclic alkyl group (acycloalkyl group), or alkyl group comprising a cyclic moiety (acycloalkyl-alkyl group or an alkyl-cycloalkyl group). As the alkyl grouphaving 1 to 5 carbon atoms, there may be mentioned, for example, methyl,ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl,n-pentyl, isopentyl, 1-methyl-butyl, 2-methyl-butyl, cyclopropyl,cyclobutyl, cyclopentyl, 2-cyclopropyl-ethyl, or 1-cyclobutyl-methyl.

[0031] The benzyl group as used herein may be unsubstituted or have oneor more substituents. When the benzene group has one or moresubstituents, the benzene group may be substituted with 1 to 5substituents (preferably 1 to 2 substituents) of an alkyl group having 1to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and/or ahalogen atom (such as fluorine, chlorine, bromine, or iodine). Thesesubstituents preferably exist on the phenyl group.

[0032] The alkyl-carbonyl group in which the alkyl moiety has 1 to 4carbon atoms (hereinafter referred to as C₁₋₄ alkyl-carbonyl group) asused herein may be unsubstituted or have one or more substituents. Thealkyl moiety having 1 to 4 carbon atoms in a substituted C₁₋₄alkyl-carbonyl group may be substituted with one or more alkoxy groupshaving 1 to 4 carbon atoms and/or halogen atoms (fluorine, chlorine,bromine, or iodine). When the alkyl moiety of the C₁₋₄ alkyl-carbonylgroup is substituted with one or more alkoxy groups having 1 to 4 carbonatoms, the number of the substituents is preferably 1 to 2.

[0033] When the alkyl moiety of the C₁₋₄ alkyl-carbonyl group issubstituted with one or more halogen atoms, it may be substituted withone to a certain number (i.e., a number of substitutable hydrogen atoms)of fluorine, chlorine, bromine, and/or iodine groups. When it issubstituted with a kind of halogen atom, the number of substitutedfluorine atoms is preferably 1 to a number of substitutable hydrogenatoms, the number of substituted chlorine atoms is preferably 1 to 3,and the number of substituted bromine or iodine atoms is preferably 1 to2. When it is substituted with plural kinds of halogen atoms, it ispreferable that each of the above preferable number in the case ofsubstitution with a kind of halogen atom is combined, within a number ofsubstitutable hydrogen atoms.

[0034] When it is substituted with plural kinds of substituents, it ispreferable that each of a preferable number of substitutions iscombined.

[0035] In the general formula (1), it is preferable that R¹ is a methylgroup, a benzyl group, or an acetyl group, R² is a hydrogen atom or anacetyl group, and R³ is a hydrogen atom or an acetyl group. Further, itis more preferable that R¹ is a benzyl group, R² is a hydrogen atom oran acetyl group, and R³ is a hydrogen atom or an acetyl group.

[0036] As concrete examples of the trihydroxybenzaldehyde compound ofthe general formula (1), there may be mentioned, for example,

[0037] 2,4,5-trihydroxybenzaldehyde,

[0038] 4-methyloxy-2,5-dihydroxybenzaldehyde,

[0039] 4-ethyloxy-2,5-dihydroxybenzaldehyde,

[0040] 4-propyloxy-2,5-dihydroxybenzaldehyde,

[0041] 4-butyloxy-2,5-dihydroxybenzaldehyde,

[0042] 4-benzyloxy-2,5-dihydroxybenzaldehyde,

[0043] 4,5-dimethyloxy-2-hydroxybenzaldehyde,

[0044] 4,5-methylenedioxy-2-hydroxybenzaldehyde, or

[0045] 5-hydroxy-6-formyl-2,2-dimethyl-1,3-benzodioxole, or acetylatedcompounds of the above compounds, such as

[0046] 2,4,5-triacetoxybenzaldehyde,

[0047] 2-acetoxy-4,5-hydroxybenzaldehyde,

[0048] 2,5-diacetoxy-4-benzyloxybenzaldehyde, or the like.

[0049] The process of the present invention for manufacturing anesculetin compound is carried out in an aprotic polar solvent. Theaprotic polar solvent is not particularly limited, so long as it isinert in the reaction system of the present invention. As the aproticpolar solvent, there may be mentioned, for example,N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide,N,N-diethylacetamide, 1-methyl-2-pyrrolidinone,1,1,3,3,-tetramethylurea, or 1,3-dimethyl-2-imidazolidinone.N,N-dimethylformamide, N,N-diethylformamide, 1,1,3,3,-tetramethylurea,or 1,3-dimethyl-2-imidazolidinone may be preferably used.

[0050] The process of the present invention for manufacturing anesculetin compound is carried out in the presence of a weak base. Theweak base is not particularly limited, but there may be mentioned, forexample, alkali metal salts (such as sodium acetate or potassiumacetate) of organic acids (such as carboxylic acid or oxalic acid),alkali metal salts (such as potassium carbonate, sodiumhydrogencarbonate, or lithium carbonate) of inorganic acids, orN-containing aromatic heterocyclic compound (such as pyridine,quinoline, or dimethylaminopyridine).

[0051] In the process of the present invention for manufacturing anesculetin compound, the trihydroxybenzaldehyde compound of the generalformula (1) is cyclocondensed by acetic anhydride or a compound whichforms acetic anhydride in the reaction system.

[0052] The term “compound which forms acetic anhydride in the reactionsystem” as used herein is a compound which reacts with the weak base toform acetic anhydride in a step of the process of the present inventionfor manufacturing an esculetin compound. As the compound, there may bementioned, for example, acetyl halide (such as acetyl chloride or acetylbromide).

[0053] When acetic anhydride is used in the process of the presentinvention for manufacturing an esculetin compound, with respect to thetrihydroxybenzaldehyde compound of the general formula (1), 0.5 to 8equivalents (preferably 3 to 4 equivalents) of acetic anhydride may beused in the presence of 1 to 10 equivalents (preferably 3 to 4equivalents) of the weak base (such as sodium acetate).

[0054] When the compound which forms acetic anhydride in the reactionsystem (such as acetyl halide) is used, with respect to thetrihydroxybenzaldehyde compound of the general formula (1), 1 to 10equivalents (preferably 3 to 4 equivalents) of the compound which formsacetic anhydride (such as acetyl halide) may be used in the presence of2 to 10 equivalents (preferably 3 to 4 equivalents) of the weak base(such as sodium acetate).

[0055] A feature of the process of the present invention is that, evenif a trihydroxybenzaldehyde compound in which one or more acetoxy groupsbind to 3- and/or 4-positions is used as a starting material, anesculetin compound in which one or more acetoxy groups at 6- and/or7-positions of coumarin are converted to hydroxyl groups can beobtained, as a product, by using preferable reaction conditions (or morepreferable reaction conditions) described in the present specification.

[0056] The process of the present invention for manufacturing anesculetin compound may be carried out under atmospheric conditions, butpreferably in an inert gas (such as a nitrogen gas or an argon gas)atmosphere. The reaction temperature and the reaction time may bechanged in accordance with a starting material used, but the reaction iscarried out while heating at preferably 100 to 200° C., more preferably150 to 180° C. for generally 1 to 24 hours, preferably 2 to 5 hours.

[0057] The trihydroxybenzaldehyde compound of the general formula (1),which is used as a starting material in the process of the presentinvention for manufacturing an esculetin compound, can be manufacturedby performing a formylation of the trihydroxybenzene compound of thegeneral formula (3).

[0058] The formylation can be carried out by a known method per se, forexample, by treating it with an agent for formylation, if necessary inthe presence of an appropriate catalyst. As the agent for formylation,for example, trialkyl orthoformate may be used. As the catalyst, forexample, aluminum halide may be used.

[0059] The formulation is preferably carried out in an ethereal oraromatic organic solvent. More particularly, ether, dimethoxyethane,dioxane, tetrahydrofuran, toluene, ethylbenzene, xylene, orchlorobenzene may be preferably used. The formylation may be carried outunder atmospheric conditions, but preferably in an inert gas (such as anitrogen gas or an argon gas) atmosphere. The reaction temperature andthe reaction time may be changed in accordance with a starting materialused, but the reaction is carried out at preferably 0 to 40° C., morepreferably 0 to 10° C. for generally 0.1 to 10 hours, preferably 0.1 to1 hour.

[0060] Among the trihydroxybenzene compound of the general formula (3)as one of intermediates of esculetin compounds of the present inventionused in the manufacture of the trihydroxybenzaldehyde compound of thegeneral formula (1), the trihydroxybenzene compound of the generalformula (30) is a novel compound. The trihydroxybenzene compound of thegeneral formula (30) can be prepared by a known method per se.

[0061] For example, the compound of the general formula (30) wherein R³¹is a benzyl group, R³² is an acetyl group, and R³³ is a hydrogen atom oran acetyl group can be obtained, for example, by oxidizing known2-benzyloxyphenol, using a Fremy salt (i.e., potassium nitrososulfonate)or by bubbling oxygen in the presence of a cobalt complex [TetrahedronLetters, vol. 30, 5929(1989)], to form 2-benzyloxy-1,4-benzoquinone, andthen by performing reductive acetoxylation of2-benzyloxy-1,4-benzoquinone with zinc powder or the like in thepresence of acetic anhydride and pyridine. In this connection, theacetyl group can be easily hydrolyzed with hydrochloric acid or thelike.

[0062] Further, the compound of the general formula (30) wherein R³¹ andR³² together form a —CH₂— group or a —C(CH₃)₂— group, and R³³ is ahydrogen atom or an acetyl group can be obtained, for example, byreacting 1,2,4-trihydroxybenzene with dichloromethane and cesiumfluoride in dimethylformamide, or by reacting 1,2,4-trihydroxybenzenewith 2,2-dimethoxypropane in the presence of an acid catalyst.

[0063] Among the trihydroxybenzaldehyde compound of the general formula(1) as one of intermediates of esculetin compounds of the presentinvention used as a starting material in the process of the presentinvention for manufacturing an esculetin compound, thetrihydroxybenzaldehyde compound of the general formula (10) is a novelcompound. The trihydroxybenzaldehyde compound of the general formula(10) can be prepared by a known method per se.

[0064] For example, the trihydroxybenzaldehyde compound of the generalformula (10) may be prepared by performing a formylation of acorresponding trihydroxybenzene compound. More particularly, forexample, the compound of the general formula (10) wherein R¹¹ is analkyl group having 2 to 5 carbon atoms, R¹² is a hydrogen atom, and R¹³is a hydrogen atom can be easily obtained by performing a formylation ofknown 2-alkyloxyhydroquinone with triethyl orthoformate ester or thelike in the presence of aluminum chloride. Further, the compound of thegeneral formula (10) wherein R¹¹ and R¹² together form a —C(CH₃)₂—group, and R¹³ is a hydrogen atom may be easily by performing aformylation of 5-hydroxy(or acetyloxy)-2,2-dimethyl-1,3-benzodioxol in asimilar fashion.

[0065] In this connection, the compound in which R¹³ is an acetyl groupcan be obtained by acetylating the resulting product in the accordancewith a conventional method.

[0066] Among the trihydroxybenzaldehyde compounds of the general formula(1), methods for manufacturing typical known compounds will beexplained. For example, 2,4,5-trihydroxybenzaldehyde, which correspondsto the compound of the general formula (1) wherein R¹ is a hydrogenatom, is commercially available (TOKYO KASEI KOGYO CO., LTD. or thelike), or may be easily obtained by performing a formylation ofcommercially available 1,2,4-trihydroxybenzene with triethylorthoformate ester or the like in the presence of aluminum chloride.Further, 4-methyloxy-2,5-dihydroxybenzaldehyde, which corresponds to thecompound of the general formula (1) wherein R¹ is a methyl group, may beeasily obtained by performing a formylation of commercially available2-methyloxy-hydroquinone in a similar fashion. Furthermore,4-benzyloxy-2,5-dihydroxybenzaldehyde, which corresponds to the compoundof the general formula (1) wherein R¹ is a benzyl group, may be easilyobtained by performing benzylation of 2,4,5-hydroxybenzaldehyde, or byperforming a formylation of 2-benzyloxyhydroquinone.

[0067] Further, 4,5-dimethyloxy-2-hydroxybenzaldehyde, which correspondsto the compound of the general formula (1) wherein R¹ and R² are methylgroups, may be easily obtained by performing a formylation of3,4-dimethoxyphenol in a similar fashion. Furthermore,4,5-methylenedioxy-2-hydroxybenzaldehyde, which corresponds to thecompound of the general formula (1) wherein R¹ and R² together form a—CH₂— group, may be easily obtained by performing a formylation ofcommercially available sesamol in a similar fashion.

[0068] Further, 2,4,5-triacetoxybenzaldehyde,2-acetoxy-4,5-hydroxybenzaldehyde, or2,5-diacetoxy-4-benzyloxybenzaldehyde, which corresponds to the compoundof the general formula (1) wherein R¹, R², and/or R³ are acetyl groups,may be obtained by acetylating 2,4,5-trihydroxybenzaldehyde or4-benzyloxy-2,5-dihydroxybenzaldehyde with acetic anhydride and sodiumacetate or with acetyl chloride and sodium acetate.

[0069] Among the esculetin compound of the general formula (2) obtainedin the process of the present invention for manufacturing an esculetincompound, the esculetin compound of the general formula (20) is a novelcompound. The novel esculetin compound of the general formula (20) canbe prepared by the process of the present invention for manufacturing anesculetin compound.

[0070] The trihydroxybenzaldehyde compound of the general formula (10),the esculetin compound of the general formula (20), and thetrihydroxybenzene compound of the general formula (30) exhibit anantifungal activity and an herbicidal activity, and thus can be used asan active ingredient of an antifungal agent for agriculture andhorticulture or an herbicide.

[0071] When the above compound is used as an antifungal agent foragriculture and horticulture or an antifungal composition foragriculture and horticulture, or an herbicide or an herbicidecomposition, the compound may be used alone, but is generally formulatedand used with one or more adjuvants in various forms, such as dust,water dispesible powder, granules, emulsifiable concentrate, or thelike. The formulation is prepared so that it contains preferably 0.1 to95 weight %, more preferably 0.5 to 90 weight %, most preferably 2 to 70weight % of one or more kinds of the trihydroxybenzaldehyde compound ofthe general formula (10), the esculetin compound of the general formula(20), and/or the trihydroxybenzene compound of the general formula (30).

[0072] A carrier, a diluent, or a surfactant which can be used as theadjuvant is as follows. As a solid carrier, there may be mentioned, forexample, talc, kaolin, bentonite, diatomaceous earth, white carbon,clay, or the like. As a liquid diluent, there may be mentioned, forexample, water, toluene, xylene, cyclohexane, chlorobenzene, loweralcohols, cyclohexanone, N,N-dimethylformamide, N-methylpyrrolidone,dimethylsulfoxide, or the like. As the surfactant, it is preferable toselect an appropriate surfactant in accordance with its effect. Forexample, as an emulsifying agent, polyoxyethylene alkyl aryl ether,polyoxyethylene sorbitan monolaurate, or the like is preferable. As adispersing agent, lignin sulfonate, dibutylnaphthalene sulfonate, or thelike is preferable. As a wetting agent, there may be mentioned, forexample, alkyl sulfonate, alkylphenyl sulfonate, or the like.

[0073] The antifungal agent for agriculture and horticulture or theantifungal composition for agriculture and horticulture, or theherbicide or the herbicide composition can be used directly, or afterdiluting it with a diluent such as water or the like to a predeterminedconcentration. When it is diluted and used, the concentration of thetrihydroxybenzaldehyde compound of the general formula (10), theesculetin compound of the general formula (20), and thetrihydroxybenzene compound of the general formula (30) is preferably0.001 to 1.0%. The amount to be used of the trihydroxybenzaldehydecompound of the general formula (10), the esculetin compound of thegeneral formula (20), and the trihydroxybenzene compound of the generalformula (30) may be appropriately selected in accordance with conditionsof cultivation. It is preferably 20 to 5000 g, more preferably 50 to1000 g per 1 ha of a land for agriculture and horticulture, such as afield, a paddy field, a fruit farm, a greenhouse, or the like. Theconcentration and the amount to be used will be changed in accordancewith a form, a season, a method, a place, or a plant, and thus it can beincreased or decreased beyond the above range. Thetrihydroxybenzaldehyde compound of the general formula (10), theesculetin compound of the general formula (20), and thetrihydroxybenzene compound of the general formula (30) may be used incombination with other active ingredients, such as a bactericide, aninsecticide, a tickicide, an herbicide, a fertilizer, or an ameliorant.

[0074] A method and a period for application are not particularlylimited. For example, it can be sprayed on the soil before or afterseeding of the plant, or after germination or growth of the plant.

EXAMPLES

[0075] The present invention now will be further illustrated by, but isby no means limited to, the following Examples.

Example 1

[0076] Synthesis of Esculetin

[0077] The reaction procedure of the present example is shown asfollows. In the following reaction procedures, DMF is dimethylformamide,and Ac₂O is acetic anhydride.

[0078] The actual procedures are as follows.

[0079] To an eggplant type flask (50 mL), 2,4,5-trihydroxybenzaldehyde(2.6 g, 16.9 mmol, 1.0 equivalent), sodium acetate (4.15 g, 50.7 mmol,3.0 equivalents), acetic anhydride (6.4 mL, 67.6 mmol, 4.0 equivalents),and dried DMF (26 mL) were added. The mixture was stirred in a nitrogenatmosphere at 180° C. for 5 hours, whereupon the starting materials werecompletely dissolved. The heating was stopped and the mixture was cooledto room temperature.

[0080] The reaction liquid was poured into a 10% hydrochloric acidaqueous solution (100 mL), and extracted with ethyl acetate (60 mL×10).The resulting organic layer was washed with distilled water (150 mL×1)and saturated brine (150 mL×1), and dried over sodium sulfate.

[0081] The solvent was evaporated under a reduced pressure, and ethylacetate (10 mL) was added. The precipitated crystals were collected toobtain esculetin (2.16 g, yield=80%) as pale brown crystals.

[0082] TLC: Rf=0.57 (CHCl₃:MeOH:CH₃COOH:H₂O=16:8:1:2) ¹H-NMR (d₆-DMSO, δppm): 6.15 (d, 1H, J=9.3 Hz, H-3), 6.72 (s, 1H, H-5), 6.96 (s, 1H, H-8),7.85 (d, 1H, J=9.3 Hz, H-4) IR (KBr cm⁻¹): 3232, 2364, 1672, 1626, 1564,1524, 1460, 1404, 1282, 1200, 1148, 946, 878, 848, 820, 748, 670, 636,576, 508, 454, 418

Example 2

[0083] Synthesis of 6-hydroxy-7-methyloxycoumarin (Isoscopoletin)

[0084] The reaction procedure of the present example is shown asfollows. In the following reaction procedures, Me is a methyl group, andAcCl is acetyl chloride.

[0085] The actual procedures are as follows.

[0086] To an eggplant type flask, a mixture of sodium acetate (443 mg,5.4 mmol, 5.0 equivalents) and dried DMF (26 mL) was added. Acetylchloride (0.23 mL, 3.24 mmol, 3.0 equivalents) was added dropwise in anitrogen gas stream under stirring while cooling on ice. After stirringat room temperature for 10 minutes, a solution of2,5-dihydroxy-4-methoxybenzaldehyde (167 mg, 1.08 mmol, 1.0 equivalent)in dimethylformamide (DMF) (0.66 mL×3) was added dropwise to thereaction system. The mixture was stirred in a nitrogen atmosphere at180° C. for 2 hours, whereupon the starting materials were completelydissolved. The heating was stopped and the mixture was cooled to roomtemperature.

[0087] The reaction liquid was poured into a 10% hydrochloric acidaqueous solution (30 mL) while cooling on ice, and extracted with ethylacetate (20 mL×6). The resulting organic layer was washed with distilledwater (50 mL×3) and saturated brine (50 mL×3), and dried over sodiumsulfate.

[0088] The solvent was evaporated under a reduced pressure, and theprecipitated crystals were washed with toluene, and then collected toobtain isoscopoletin (154 mg, yield=79%) as pale brown crystals.

[0089] TLC: Rf=0.29 (n-hexane/ethyl acetate=1:1) ¹H-NMR (CDCl₃, δ ppm):3.90 (s, 3H, CH₃O), 6.18 (d, 1H, J=9.3 Hz, H-3), 6.90 (s, 1H, H-5), 6.91(s, 1H, H-8), 7.75 (d, 1H, J=9.3 Hz, H-4)

Example 3

[0090] Synthesis of 7-benzyloxy-6-hydroxycoumarin (7-benzylesculetin)

[0091] The reaction procedure of the present example is shown asfollows. In the following reaction procedures, Bn is a benzyl group.

[0092] The actual procedures are as follows.

[0093] To an eggplant type flask (50 mL),4-benzyloxy-2,5-dihydroxybenzaldehyde (488.48 mg, 2.0 mmol, 1.0equivalent), sodium acetate (492.2 mg, 6.0 mmol, 3.0 equivalents),acetic anhydride (816.8 mg, 8.0 mmol, 4.0 equivalents), and dried DMF(10 mL) were added. The mixture was stirred in a nitrogen atmosphere at180° C. for 5 hours, whereupon the starting materials were completelydissolved. The heating was stopped and the mixture was cooled to roomtemperature.

[0094] The reaction liquid was poured into a 1% hydrochloric acidaqueous solution (20 mL), and extracted with ethyl acetate (100 mL×1).The resulting organic layer was washed with distilled water (20 mL×3)and saturated brine (20 mL×3), and dried over sodium sulfate (10 g) toobtain a crude product (652.2 mg).

[0095] The solvent was evaporated under a reduced pressure, and theresulting residue was purified by silica gel chromatography[3.0(diameter)×7 cm, 20 g; n-hexane:ethyl acetate (5:1-2:1); 300 mL+120mL] to obtain 7-benzylesculetin (390 mg, 72.7%) as pale brown crystals(yield: 72.7%).

[0096] TLC: Rf=0.15 (n-hexane/ethyl acetate=2:1) ¹H-NMR (CDCl₃, δ ppm):5.19 (s, 2H, CH₂Ph) , 5.66 (s, 1H, OH), 6.29 (d, J=9.77 Hz, 1H, H-3),6.90 (s, 1H, Ar-H), 6.99 (s, 1H, Ar—H), 7.3-7.4 (br, 1H, Ph), 7.60 (d,J=9.77 Hz, 1H, H-4) IR (KBr cm⁻¹): 3232, 2304, 1694, 1624, 1566, 1512,1472, 1456, 1402, 1386, 1360, 1320, 1292, 1210, 1150, 1106, 986, 942,888, 828, 744, 700, 630, 594, 572, 478

[0097] Esculetin can be quantitatively obtained by hydrogenolyzing theresulting 7-benzylesculetin with hydrogen in the presence of 10% Pd/C inmethanol.

Example 4

[0098] Synthesis of Esculetin

[0099] The reaction procedure of the present example is shown asfollows.

[0100] The actual procedures are as follows.

[0101] To absolution of 2,4,5-triacetoxybenzaldehyde (455 mg, 1.62 mmol)in DMF (9.0 mL, 0.18 mol/l), acetic acid (0.19 mL, 2.0 equivalents),sodium acetate (267 mg, 2.0 equivalents), and acetic anhydride (0.18 mL,1.2 equivalents) were added, and the mixture was reacted at 180° C. for5 hours. After dissolution of the starting materials was confirmed bythin layer chromatography (TLC), a 10% hydrochloric acid aqueoussolution (100 mL) was added, and then the reaction mixture was extractedwith ethyl acetate (80 mL×8). The combined organic layer was washed withdistilled water (100 mL) and saturated brine (100 mL), dried over sodiumsulfate, and then concentrated under a reduced pressure (azeotropy withtoluene) to obtain brown crystals (301 mg). The content of esculetin wasfound to be 74%, by determining the crystals by HPLC. Therefore, theactual yield of esculetin was 75% by calculation.

Example 5

[0102] Synthesis of 7-benzyloxy-6-hydroxycoumarin

[0103] The reaction procedure of the present example is shown asfollows. In the following reaction procedures, Bn is a benzyl group, andAcCl is acetyl chloride.

[0104] The actual procedures are as follows.

[0105] To an eggplant type flask (25 mL),4-benzyloxy-2,5-dihydroxybenzaldehyde (164 mg, 0.5 mmol, 1.0equivalent), sodium acetate (82 mg, 1 mmol, 2.0 equivalents), and driedDMF (4 mL) were added. To the mixture, a solution of acetic anhydride(204 mg, 2 mmol, 4.0 equivalents) in DMF (1.5 mL) was slowly addeddropwise at room temperature. The mixture was stirred in a nitrogenatmosphere at 180° C. for 4 hours. After the reaction, the reactionliquid was cooled to room temperature.

[0106] To the reaction liquid, ethyl acetate (60 mL) and water (30 mL)were added and widely distributed. After separating an aqueous layer,the resulting organic layer was washed with saturated brine (10 mL×3),and dried over sodium sulfate (5 g).

[0107] The solvent was evaporated under a reduced pressure, and theresulting residue (191.8 mg) was purified by silica gel chromatography[2.5(diameter)×2 cm, 5 g; n-hexane:ethyl acetate (1:2)] to obtain7-benzylesculetin (119.4 mg). Brown and powdery crystals (100.3 mg,yield=74.7%) were obtained by washing with n-hexane.

[0108] TLC: Rf=0.18 (n-hexane/ethyl acetate=2:1)

[0109] Esculetin can be quantitatively obtained by hydrogenolyzing theresulting 7-benzylesculetin with hydrogen in the presence of 10% Pd/C inmethanol.

Example 6

[0110] (1) Synthesis of Methylenedioxycoumarin

[0111] The reaction procedure of synthesis of methylenedioxycoumarin isshown as follows.

[0112] The actual procedures are as follows.

[0113] To an eggplant type flask (25 mL),4,5-methylenedioxysalicylaldehyde (83.06 mg, 0.5 mmol, 1.0 equivalent),sodium acetate (123.03 mg, 1.5 mmol, 3.0 equivalents), acetic anhydride(204.18 mg, 2.0 mmol, 4.0 equivalents), and dried DMF (5 mL) were added.The mixture was stirred in a nitrogen atmosphere at 170° C. for 5 hours,whereupon the starting materials were almost dissolved. The heating wasstopped and the mixture was cooled to room temperature.

[0114] The reaction liquid was poured into a 1% hydrochloric acidaqueous solution (10 mL), and extracted with ethyl acetate (40 mL×1).The resulting organic layer was washed with saturated brine (20 mL×2),and dried over sodium sulfate (5 g).

[0115] The solvent was evaporated under a reduced pressure, and theresulting residue was purified by silica gel chromatography[2.5(diameter)×8 cm, 20 g; n-hexane:ethyl acetate (3:1); 150+50 mL)] toobtain methylenedioxycoumarin (64.3 mg, yield=67.6%) as light browncrystals.

[0116] Melting point: 198-205° C. (decomposition) TLC: Rf=0.27(n-hexane/ethyl acetate=2:1) ¹H-NMR (CDCl₃, δ ppm): 6.07 (s, 6H, Me₂),6.26 (d, J=9.76 Hz, 1H), 6.82 (s, 2H), 7.56 (d, J=9.76 Hz, 1H) IR (KBrcm⁻¹): 3072, 2928, 1712, 1636, 1584, 1494, 1456, 1420, 1388, 1318, 1272,1260, 1228, 1188, 1162, 1124, 1082, 1040, 942, 922, 884, 850, 838, 766,752, 732, 552, 514

[0117] (2) Synthesis of Esculetin

[0118] The reaction procedure of synthesis of esculetin is shown asfollows. In the following reaction procedures, EtSH is ethanethiol.

[0119] The actual procedures are as follows.

[0120] To an eggplant type flask (25 mL), ethanethiol (2 mL) andaluminum tribromide (320.9 mg, 1.2 mmol, 4.8 equivalents) were added andcooled to 0° C. While stirring, 6,7-methylenedioxycoumarin (47.5 mg,0.25 mmol, 1.0 equivalent) was added in one portion. The reaction liquidwas changed in color from pale brown to brown. The reaction liquid wasstirred at 0° C. for 2 hours, and then stirred in a draft at roomtemperature overnight to evaporate ethanethiol.

[0121] A 10% hydrochloric acid aqueous solution (10 mL) was added to theresulting residue to form a light brown precipitate. After stirringovernight, extraction with ethyl acetate (20 mL×2) was carried out. Theresulting organic layer was washed with saturated brine (10 mL×2), anddried over sodium sulfate (5 g).

[0122] The solvent was evaporated under a reduced pressure, and theresulting residue (41.6 mg) was purified by silica gel chromatography[2.5(diameter)×1 cm, 2 g; ethyl acetate] to obtain esculetin (37.6 mg,yield=84.4%) as light brown crystals. The IR spectrum of the compoundaccorded with that of the standard.

[0123] TLC: Rf=0.57 (CHCl₃:MeOH:CH₃COOH:H₂O=16:8:1:2:) IR (KBr cm⁻¹):3232, 2364, 1672, 1626, 1564, 1524, 1460, 1404, 1282, 1200, 1148, 946,878, 848, 820, 748, 670, 636, 576, 508, 454, 418, 552

Example 7

[0124] (1) Synthesis of Esculetin Acetonide

[0125] The reaction procedure of synthesis of esculetin acetonide isshown as follows.

[0126] The actual procedures are as follows.

[0127] To an eggplant type flask (100 mL),2,2-dimethyl-5formyl-6-hydroxy-1,3-benzodioxole (164.3 mg, 0.85 mmol,1.0 equivalent), sodium acetate (278 mg, 3.38 mmol, 4.0 equivalents),acetic anhydride (259 mg, 2.54 mmol, 3.0 equivalents), and dried DMF (10mL) were added. The mixture was stirred in a nitrogen atmosphere at 170°C. for 5 hours, whereupon the starting materials were almost dissolved.The heating was stopped and the mixture was cooled to room temperature.

[0128] The reaction liquid was poured into distilled water (40 mL) withfloating ice, and extracted with ethyl acetate (40 mL×2). The resultingorganic layer was washed with distilled water (20 mL×3) and saturatedbrine (20 mL×1), and dried over sodium sulfate (5 g).

[0129] The solvent was evaporated under a reduced pressure, and theresulting residue (200.2 mg) was purified by silica gel chromatography[2.5(diameter)×4 cm, 10 g; n-hexane:ethyl acetate (6:1); 180+30 mL)] toobtain esculetin acetonide (158.1 mg, yield=85.7%) as light browncrystals.

[0130] Melting point: 178-180° C. TLC: Rf=0.35 (n-hexane/ethylacetate=2:1) ¹H-NMR (CDCl₃, δ ppm): 1.72 (s, 6H, Me₂), 6.25 (d, J=9.76Hz, 1H), 6.74 (s, 1H), 6.75 (s, 1H), 7.57 (d, J=9.76 Hz, 1H) IR (KBrcm⁻¹): 3064, 3012, 2364, 1726, 1628, 1580, 1504, 1454, 1410, 1386, 1342,1284, 1230, 1198, 1150, 1106, 1064, 982, 924, 890, 840, 824, 782, 754,724, 650, 604, 558, 502, 464, 450

[0131] (2) Synthesis of Esculetin

[0132] The reaction procedure of synthesis of esculetin is shown asfollows.

[0133] The actual procedures are as follows.

[0134] To an eggplant type flask (100 mL), esculetin acetonide (67.1 mg,0.31 mmol, 1.0 equivalent) and a 6N hydrochloric acid aqueous solution(1 mL) were added. The mixture was stirred in a nitrogen atmosphere at120° C. for 2 hours, whereupon the starting materials were almostdissolved. The heating was stopped and the mixture was cooled to roomtemperature.

[0135] The reaction liquid was poured into distilled water (10 mL) withfloating ice, and extracted with ethyl acetate (20 mL×3). The resultingorganic layer was washed with distilled water (10 mL×3) and saturatedbrine (10 mL×1), and dried over sodium sulfate (5 g). The solvent wasevaporated under a reduced pressure, and the resulting residue waspurified by silica gel chromatography [1.7(diameter)×5 cm, 4 g; ethylacetate] to obtain esculetin (39.4 mg, yield=72.0%) as light browncrystals.

[0136] TLC: Rf=0.57 (CHCl₃:MeOH:CH₃COOH:H₂O=16:8:1:2) IR (KBr cm⁻¹):3352, 1671, 1623, 1569, 1404, 1368, 1284, 1149, 948, 879, 849, 822, 672,636, 579

[0137] When deprotection reaction was attempted using an acetic acid:distilled water (4:1) mixture instead of the 6N hydrochloric acidaqueous solution, the reaction rate thereof was slow. However, after thereaction was completed, the resulting residue was purified by silica gelchromatography [1.7(diameter)×5 cm, 4 g; ethyl acetate] to obtainesculetin (62.2 mg, yield=83.7%) as light brown crystals.

[0138] TLC: Rf=0.57 (CHCl₃:MeOH:CH₃COOH:H₂O=16:8:1:2) IR (KBr cm⁻¹):2364, 1672, 1626, 1572, 1404, 1366, 1284, 1200, 1150, 948, 878, 848,822, 670, 636, 578

[0139] [Synthetic Examples of Aldehyde Compounds as a Starting Material]

Synthetic Example 1

[0140] 2,5-dihydroxy-4-methoxybenzaldehyde (The Starting Material inExample 2)

[0141] The reaction procedure of the present synthetic example is shownas follows.

[0142] The actual procedures are as follows.

[0143] Trimethyl orthoformate (2.89 mL, 6.0 equivalents) was addeddropwise to methoxyhydroquinone (618 mg, 4.41 mmol), and then ether(15.5 mL) was further added. After methoxyhydroquinone was completelydissolved, the reaction system was placed in a water bath, and aluminumchloride (882 mg, 1.5 equivalents) was added in a nitrogen gas streamunder stirring. After the reaction was carried out for 10 minutes, a 10%hydrochloric acid (50 mL) was added, and then extraction with ether (30mL×3) and washing with water (50 mL×3) and saturated brine (50 mL×3)were carried out. The resulting organic layer was dried over sodiumsulfate, and concentrated under a reduced pressure to obtain2,5-dihydroxy-4-methoxybenzaldehyde (166 mg, yield=24.5%) as lightyellow crystals.

[0144]¹H-NMR (CD₃OD): δ 3.85 (3H, s, CH₃O—), 6.44 (1H, s, H-3), 6.94(1H, s, H-6), 9.66 (1H, s, —CHO)

Synthetic Example 2

[0145] Synthesis of 4-benzyloxy-5-hydroxysalicylaldehyde (The StartingMaterial in Example 3)

[0146] The reaction procedure of the present synthetic example is shownas follows. In the following reaction procedures, MEK is methyl ethylketone.

[0147] The actual procedures are as follows.

[0148] To an eggplant type flask (50 mL), 2,4,5-trihydroxybenzaldehyde(154 mg, 1.0 mmol, 1.0 equivalent), sodium hydrogencarbonate (126 mg,1.5 mmol, 1.5 equivalents), potassium iodide (33 mg, 0.2 mmol, 0.2equivalent), and methyl ethyl ketone (MEK; 10 mL) were added. To thissolution, benzyl chloride (189.9 mg, 1.5 mmol, 1.5 equivalents) wasadded portionwise at room temperature.

[0149] The reaction liquid was heated at reflux in a nitrogen atmosphereat 105° C. for 22 hours in total. The starting materials appeared to becompletely dissolved, and thus the reaction liquid was evaporated undera reduced pressure.

[0150] An acid aqueous solution (10 mL, a 1% hydrochloric acid aqueoussolution) was poured, and extraction with ethyl acetate (30 mL×1) wascarried out. An organic layer was washed with saturated brine (10 mL×1),distilled water (10 mL×1), and further saturated brine(10 mL×1), driedover sodium sulfate (5 g), and concentrated under a reduced pressure toobtain a crude product (297.8 mg) . The crude product was purified bysilica gel chromatography [1.7(diameter)×8 cm, 6 g; n-hexane:ethylacetate (4:1)] to obtain 4-benzyloxy-5-hydroxysalicylaldehyde (219.1 mg,yield=89.7%) as pale brown crystals.

[0151] Melting point: 144-145° C. TLC: Rf=0.5 (n-hexane/ethylacetate=2:1) ¹H-NMR (CDCl₃, δ ppm): 5.15 (s, 2H, PhCH₂), 6.54 (s, 1H,Ar—H), 7.04 (s, 1H, Ar—H), 7.42 (s, 5H, Ph), 9.67 (s, 1H, CHO) IR (KBrcm⁻¹): 3332, 1638, 1588, 1560, 1504, 1470, 1398, 1362, 1218, 1178, 1142,990, 914, 866, 834, 798, 746, 698, 602, 552, 482, 410

Synthetic Example 3

[0152] Synthesis of 2,5-dihydroxy-4-benzyloxybenzaldehyde (The StartingMaterial in Example 3)

[0153] (1) Synthesis of 2-benzyloxy-1,4-benzoquinone 1

[0154] The reaction procedure of synthesis of2-benzyloxy-1,4-benzoquinone is shown as follows.

[0155] The actual procedures are as follows.

[0156] To an eggplant type flask (100 mL), 2-(benzyloxy)phenol (200.2mg, 1.0 mmol, 1.0 equivalent) and acetone (5 mL) were added. To thisstirred solution, distilled water (15 mL) containing KH₂PO₄ (204 mg, 1.5mmol, 1.5 equivalents) was added. A Fremy salt (i.e., potassiumnitrososulfonate; 1.07 g, 4.0 mmol, 4.0 equivalents) was dissolved indistilled water (40 mL) cooled to 4° C. and containing KH₂PO₄ (544 mg,4.0 mmol, 4.0 equivalents), and the solution was quickly added dropwiseat room temperature. After the dropping was completed, the mixture wasstirred at room temperature for 3 hours, and then the solution color waschanged to dark brown and a yellow precipitate was formed. It wasobserved that the starting materials were almost dissolved at thisstage.

[0157] After the reaction was completed, ethyl acetate (40 mL×1, 20mL×1) was added, and an aqueous layer was extracted. The resultingorganic layer was washed with saturated brine (10 mL×1), dried oversodium sulfate (5 g), and concentrated under a reduced pressure toobtain crude solid crystals (224.3 mg). The crude crystals were purifiedby silica gel chromatography [21.7(diameter)×7.5 cm, 6 g; n-hexane:ethylacetate (6:1)] to obtain 2-benzyloxy-1,4-benzoquinone (182.9 mg,yield=83.4%) as pale brown crystals.

[0158] TLC: Rf=0.41 (n-hexane/ethyl acetate=2:1 ¹H-NMR (CDCl₃, δ ppm):5.05 (s, 2H, CH₂Ph) , 6.00 (s, 1H, H-3), 6.71 (s, 2H, H-5, 6), 7.40 (s,5H, Ph—) IR (KBr cm⁻¹): 3080, 2344, 1674, 1642, 1596, 1504, 1454, 1386,1360, 1316, 1248, 1210, 1112, 1004, 886, 836, 728, 692, 466, 424

[0159] (2) Synthesis of 2-benzyloxy-1,4-benzoquinone 2

[0160] The reaction procedure of synthesis of 2-(benzyloxy)hydroquinoneis shown as follows.

[0161] The actual procedures are as follows.

[0162] To an eggplant type flask (100 mL), 2-benzyloxyphenol (206 mg,1.03 mmol, 1.0 equivalent) and acetonitrile (20 mL) were added. To thisstirred solution, Co(bpb)H₂O (38.5 mg, 0.098 mmol, 0.05 equivalent) wasadded at room temperature. The mixture color was changed from brownishgreen to brown. In this connection, Co(bpb)H₂O isaqua-[N,N-bis((2′-pyridine-carboxamido)-1,2-benzene]cobalt (II).

[0163] Oxygen was blown into the reaction mixture at the flow rate of100 mL/min for 24 hours in total, but the starting materials stillremained. After the reaction was completed, the solvent was concentratedunder a reduced pressure and evaporated. The resulting residue waspurified by silica gel chromatography [2.5(diameter)×4.0 cm, 10 g;n-hexane:ethyl acetate (10:1)] to obtain 2-benzyloxy-1,4-benzoquinone(93.5 mg, yield=42.4%) in Fraction Nos. 11-16 as golden crystals, andfurther obtain the starting material (114.7 mg, 55.6%) in Fraction Nos.2-4 as colorless oil. This yield corresponds to 95.5% in view of therecovery of the starting material.

[0164] TLC: Rf=0.41 (n-hexane/ethyl acetate=2:1)

[0165] (3) Synthesis of 1,4-diacetoxy-2-benzyloxybenzene The reactionprocedure of synthesis of 1,4-diacetoxy-2-benzyloxybenzene is shown asfollows.

[0166] The actual procedures are as follows.

[0167] To an eggplant type flask (25 mL), 2-benzyloxy-1,4-benzoquinone(250 mg, 1.17 mmol, 1.0 equivalent), acetic anhydride (2.5 mL, 227.0equivalents), and zinc powder (250 mg, 3.82 mmol, 3.28 equivalents) wereadded at 0° C. Pyridine (0.25 mL, 3.69 mmol, 2.64 equivalents) was addedportionwise to the solution at 0° C.

[0168] After 20 minutes, the reaction liquid color was changed from abrown precipitated state to light green, and further stirred for 45minutes.

[0169] The reaction mixture was filtered through a glass filter (3G4) toremove zinc powder and inorganic salts, and the residue was sufficientlywashed ethyl acetate. The resulting filtrate was diluted with ethylacetate, and washed with saturated sodium hydrogencarbonate (5 mL).

[0170] The organic layer was washed with distilled water (5 mL×2) andsaturated brine (5 mL×1), dried over sodium sulfate (5 g), andconcentrated under a reduced pressure to obtain a crude product (438mg). The crude product was purified by silica gel chromatography[2.5(diameter)×3 cm, 8 g; n-hexane:ethyl acetate (3:1)] to obtain1,4-diacetoxy-2-benzyloxybenzene (344.5 mg, yield=98.3%) as pale browncrystals.

[0171] TLC: Rf=0.41 (n-hexane/ethyl acetate=2:1) ¹H-NMR (CDCl₃, δ ppm):2.25 (s, 3H, COCH₃), 2.27 (s, 1H, COCH₃), 5.05 (s, 2H, PhCH₂), 6.70 (dd,J=8.30, 2.44 Hz, 1H, Ar—H-6), 6.78 (d, J=2.44 Hz, 1H, Ar—H-5), 7.04 (d,J-8.30 Hz, 1H, Ar—H-3) IR (KBr cm⁻¹): 3092, 3048, 1766, 1620, 1598,1510, 1478, 1458, 1428, 1392, 1374, 1282, 1222, 1184, 1152, 1112, 1048,1010, 972, 914, 888, 840, 826, 766, 742, 720, 700, 634, 624, 602, 588,484, 468

[0172] (4) Synthesis of 2-benzyloxy-1,4-hydroquinone

[0173] The reaction procedure of synthesis of2-benzyloxy-1,4-hydroquinone is shown as follows.

[0174] The actual procedures are as follows.

[0175] To an eggplant type flask (10 mL),1,4-diacetoxy-2-benzyloxybenzene (35.2 mg, 1.17 mmol, 1.0 equivalent)and acetone (1 mL) were added. A 2% hydrochloric acid aqueous solution(0.5 mL) was added to this stirred solution.

[0176] The mixture was heated under reflux for 4 hours.

[0177] After the reaction was completed, the solvent was removed under areduced pressure to obtain a crude product (24 mg). The crude productwas purified by silica gel chromatography [1.7(diameter)×6.5 cm, 5 g;n-hexane:ethyl acetate (2:1, 100 mL+50 mL)] to obtain2-benzyloxy-1,4-hydroquinone (18.2 mg, yield=71.8%) as colorlesscrystals.

[0178] Melting point: 99-101° C. TLC: Rf=0.24 (n-hexane/ethylacetate=2:1) ¹H-NMR (CDCl₃, δ ppm): 5.02 (s, 2H, CH₂Ph), 5.32 (br, 1H,OH, disappearance by adding heavy water), 6.31 (dd, J=8.79, 2.93 Hz, 1H,H-6), 6.50 (d, J=8 2.93 Hz, 1H, H-3), 6.78 (d, J=8.79 Hz, 1H, H-5), 7.40(s, 5H, Ph—) IR (KBr cm⁻¹): 3492, 3412, 1632, 1512, 1484, 1386, 1356,1320, 1296, 1258, 1224, 1160, 1114, 1026, 946, 832, 792, 752, 722, 706,628, 448 Elemental analysis: Calculated: C, 72.21; H, 5.59. Found: C,72.0; H, 5.5.

[0179] (5) Synthesis of 2,5-dihydroxy-4-benzyloxybenzaldehyde (TheStarting Material in Example 3)

[0180] The reaction procedure of synthesis of2,5-dihydroxy-4-benzyloxybenzaldehyde is shown as follows.

[0181] The actual procedures are as follows.

[0182] To an eggplant type flask (25 mL), 2-benzyloxyhydroquinone (108mg, 0.5 mmol, 1.0 equivalent), triethyl orthoformate (600 mg, 4.04 mmol,8 equivalents), and diethyl ether (3 mL) were added. The mixture wascooled to 8° C., and aluminum chloride (100 mg, 0.75 mmol, 1.5equivalents) was added portionwise. The reaction liquid color waschanged from light green to dark green immediately. The reaction wascarried out for 6 minutes in this state.

[0183] The starting materials were completely dissolved, and thus thereaction liquid was cooled to 0° C. An acid aqueous solution (10 mL) wasadded to the solution, and the whole was extracted with ether (40 mL×1,20 mL×1) and ethyl acetate (20 mL×2) . The resulting organic layer waswashed with distilled water (10 mL×1) and saturated brine (10 mL×1),dried over sodium sulfate (5 g), and concentrated under a reducedpressure to obtain a crude product as a solid.

[0184] The crude product was purified by silica gel chromatography[1.7(diameter)×6.5 cm, 5 g; n-hexane:ethyl acetate (5:1)] to obtain2,5-dihydroxy-4-benzyloxybenzaldehyde (76.2 mg, yield=63.2%) as lightbrown crystals.

[0185] Melting point: 147-148° C. TLC: Rf=0.44 (n-hexane/EtOH=2:1)¹H-NMR (CDCl₃, δ ppm): 5.15 (s, 2H, PhCH₂) , 6.54 (s, 1H, Ar—H), 7.04(s, 1H, Ar—H), 7.42 (s, 5H, Ph), 9.67 (s, 1H, CHO) IR (KBr cm⁻¹): 3332,1638, 1588, 1560, 1504, 1470, 1398, 1362, 1218, 1178, 1142, 990, 914,866, 834, 798, 746, 698, 602, 552, 482, 410 Elemental analysis:Calculated: C, 68.85; H, 4.95. Found: C, 69.0; H, 5.1.

Synthetic Example 4

[0186] Synthesis of 2,4,5-triacetoxybenzaldehyde (The Starting Materialin Example 4)

[0187] The reaction procedure of the present synthetic example is shownas follows.

[0188] The actual procedures are as follows.

[0189] Acetic anhydride (0.19 mL, 4.0 equivalents) was added dropwise toa solution of sodium acetate (80.7 mg, 6.0 equivalents) in DMF (0.98mL), and stirred at room temperature for 15 minutes. A solution of2,4,5-trihydroxybenzaldehyde (75.8 mg, 0.492 mmol) in DMF (0.30 mL×3)was added dropwise to the reaction system, and the reaction was carriedout at room temperature for 20 minutes. After dissolution of thestarting materials was confirmed by TLC, a 10% hydrochloric acid aqueoussolution (30 mL) was added under stirring while cooling on ice toprecipitate white crystals. The crystals were filtered through aKIRIYAMA ROHTO and washed with water to obtain2,4,5-triacetoxybenzaldehyde (135 mg, 97%) as white crystals.

Synthetic Example 5

[0190] Synthesis of 2,5-diacetoxy-4-benzyloxybenzaldehyde (The StartingMaterial in Example 5)

[0191] The reaction procedure of the present synthetic example is shownas follows.

[0192] The actual procedures are as follows.

[0193] To an eggplant type flask (100 mL),4-benzyloxy-2,5-dihydroxyaldehyde (193.8 mg, 0.793 mmol, 1.0equivalent), sodium acetate (82.05 mg, 1.0 mmol, 1.23 equivalents), anddried DMF (1 mL) were added. An acetic anhydride (204.2 mg, 2.0 mmol,2.5 equivalents) was added portionwise to the solution at roomtemperature.

[0194] The reaction liquid was stirred in a nitrogen atmosphere at roomtemperature for 2 hours, whereupon the starting materials werecompletely dissolved. Water (10 mL) was poured to form a whiteprecipitate, and the precipitate was dissolved by adding ether (20 mL)and ethyl acetate (10 mL). The resulting organic layer was washed withwater (10 mL×3), dried over sodium sulfate (5 g), and concentrated undera reduced pressure to obtain a crude product. The crude product waswashed with n-hexane to obtain 2,5-diacetoxy-4-benzyloxybenzaldehyde(236.8 mg, yield=90.89%) as pale cream crystals.

[0195] Melting point: 136-137° C. TLC: Rf=0.28 (n-hexane/ethylacetate=2:1) ¹H-NMR (CDCl₃, δ ppm): 2.27 (s, 3H, CH₃CO), 2.38 (s, 3H,CH₃CO), 5.13 (s, 2H, PhCH₂), 6.81 (s, 1H, Ar—H), 7.38 (s, 5H, Ph), 7.58(s, 1H, Ar—H), 9.95 (s, 1H, CHO) IR (KBr cm⁻¹): 2340, 1774, 1690, 1618,1510, 1424, 1370, 1328, 1284, 1216, 1156, 1102, 1008, 944, 830, 786,770, 742, 700, 668, 616, 596, 484 Elemental analysis: Calculated: C,65.85; H, 4.91. Found: C, 66.2; H, 5.0.

Synthetic Example 6:

[0196] Synthesis of 4,5-methylenedioxysalicylaldehyde (The StartingMaterial in Example 6)

[0197] The reaction procedure of the present synthetic example is shownas follows.

[0198] The actual procedures are as follows.

[0199] To an eggplant type flask (100 mL), sesamol (1.38 g, 10.0 mmol,1.0 equivalent) and ether (40 mL) were added and dissolved. Triethylorthoformate (10 mL, 7.6 mmol, 7.6 equivalents) was added to thesolution. To the resulting yellow solution, aluminum chloride (2.0 g, 15mmol, 1.5 equivalents) was added portionwise at 0° C. The mixture colorwas changed from light red to green, and further, from dark green todark blue. After 5 minutes, the mixture was cooled to 0° C., and a 5%hydrochloric acid solution (10 mL) was added. The resulting product wasslightly soluble, and the separation thereof was difficult.

[0200] The separation was carried out by adding distilled water (10 mL)and ethyl acetate (40 mL). The aqueous layer was further extracted withethyl acetate (40 mL). The collected organic layer was washed withsaturated brine (10 mL), dried over sodium sulfate (approximately 5 g),and concentrated and solidified by an evaporator to obtain a dark redsolid (1.6 g).

[0201] From the resulting dark red solid, 506.6 mg thereof was taken andpurified by silica gel chromatography [2.5(diameter)×8.0 cm, 20 g;n-hexane:ethyl acetate (3:1)] to obtain4,5-methylenedioxysalicylaldehyde (363.9 mg, yield=70.9%) in FractionNos. 2-4 as light brown needle crystals.

[0202] Melting point: 125-126° C. TLC: Rf=0.63 (n-hexane/ethylacetate=2:1) ¹H-NMR (CDCl₃, δ ppm): 6.02 (s, 6H, Me₂), 6.47 (s, 1H) ,6.86 (s, 1H), 9.62 (s, 1H, CHO) IR (KBr cm⁻¹): 3076, 1646, 1614, 1506,1482, 1424, 1388, 1314, 1270, 1230, 1162, 1086, 1036, 934, 872, 854,786, 774, 722, 710, 514

Synthetic Example 7

[0203] (1) Synthesis of 2,2-dimethyl-1,3-benzodioxol

[0204] The reaction procedure of synthesis of2,2-dimethyl-1,3-benzodioxol is shown as follows. In the followingreaction procedures, TsOH is p-toluenesulfonic acid.

[0205] The actual procedures are as follows.

[0206] To an eggplant type flask (50 mL), catechol (605 mg, 5.5 mmol,1.1 equivalents), 2,2-dimethoxypropane (520 mg, 5.0 mmol, 1.0equivalent), p-toluenesulfonic acid (approximately 2 mg), and toluene(40 mL) were added. The mixture was distilled at 130° C. for 6 hours byazeotropic distillation, but the starting materials still remained. Theheating was stopped and the mixture was cooled to room temperature. Adrop of a 28% sodium methylate in methanol solution was added toneutralize the mixture.

[0207] The solvent was removed under a reduced pressure. The resultingresidue (689.9 mg) was purified by silica gel chromatography[2.5(diameter)×4 cm, 10 g; n-hexane:ethyl acetate (4:1); 160+40 mL] toobtain 2,2-dimethyl-1,3-benzodioxol (373 mg, yield=49.6%) as yellow oil,and the starting material (216 mg, 35.8%) at the same time.

[0208] TLC: Rf=0.91 (n-hexane/ethyl acetate=2:1) ¹H-NMR (CDCl₃, δ ppm):1.67 (s, 6H, Me₂), 6.75 (m, 4H) IR (KBr cm⁻¹): 3080, 3004, 2948, 1632,1490, 1382, 1370, 1240, 1112, 1006, 978, 908, 840, 820, 786, 738, 434

[0209] (2) Synthesis of 5-hydroxy-2,2-dimethyl-1,3-benzodioxol

[0210] The reaction procedure of synthesis of5-hydroxy-2,2-dimethyl-1,3-benzodioxol is shown as follows.

[0211] The actual procedures are as follows.

[0212] To an eggplant type flask (50 mL), 1,2,4-trihydroxybenzene (630.6mg, 5.0 mmol, 1.0 equivalent), 2,2-dimethoxypropane (781 mg, 7.5 mmol,1.5 equivalents), p-toluenesulfonic acid (approximately 1 mg), andtoluene (40 mL) were added. The mixture was distilled at 130° C. for 1.5hours by azeotropic distillation, but the starting materials stillremained. The heating was stopped and the mixture was cooled to roomtemperature. A drop of a 28% sodium methylate in methanol solution wasadded to neutralize the mixture.

[0213] The solvent was removed under a reduced pressure. The resultingresidue (831.5 mg) was purified by silica gel chromatography[2.5(diameter)×4 cm, 10 g; n-hexane:ethyl acetate (4:1); 160+40 mL] toobtain 5-hydroxy-2,2-dimethyl-1,3-benzodioxol (240.9 mg, yield=28.9%) aslight brown oil, and further a by-product (45.9 mg).

[0214] TLC: Rf=0.47 (n-hexane/ethyl acetate=2:1) ¹H-NMR (CDCl₃, δ ppm):1.65 (s, 6H, , Me₂), 6.20 (dd, J=8.30, 2.45 Hz, 1H), 6.35 (d, J=2.45 Hz,1H), 6.55 (d, J=8.30 Hz, 1H) IR (KBr cm⁻¹): 3396, 3004, 1626, 1498,1382, 1224, 1160, 1118, 1074, 980, 948, 836, 788, 764, 610, 424, 884

[0215] (3) Synthesis of 2,2-dimethyl-5-formyl-6-hydroxy-1,3-benzodioxol(The Starting Material in Example 7)

[0216] The reaction procedure of synthesis of2,2-dimethyl-5-formyl-6-hydroxy-1,3-benzodioxol is shown as follows.

[0217] The actual procedures are as follows.

[0218] To an eggplant type flask (100 mL),5-hydroxy-2,2-dimethyl-1,3-benzodioxol (240 mg, 1.45 mmol, 1.0equivalent) and ether (5 mL) were added and dissolved. Triethylorthoformate ester (1.5 mL, 7.6 mmol, 7.6 equivalents) was added to thesolution. To the resulting yellow solution, aluminum chloride (289 mg,2.17 mmol, 1.0 equivalent) was added portionwise at 0° C. The mixturecolor was changed from light red to green, and further, from dark greento dark blue. After 5 minutes, the mixture was cooled to 0° C., and a 2%hydrochloric acid solution (10 mL) was added.

[0219] Ether (20 mL) was added and extraction was carried out. Thecollected organic layer was washed with distilled water (10 mL×2), driedover sodium sulfate (approximately 3 g), and concentrated and solidifiedby an evaporator to obtain a dark red solid (187.3 mg). The resultingsolid was purified by silica gel chromatography [1.7(diameter)×6.0 cm, 5g; n-hexane:ethyl acetate (10:1); 150 mL+15 mL] to obtain a fraction(106 mg, 37.6%) containing the desired product in Fraction Nos. 1-3.

[0220] Further, the fraction was purified by silica gel chromatography[1.7(diameter)×8.5 cm, 8 g; n-hexane:ethyl acetate (10:1); 100 mL+10 mL]to obtain 2,2-dimethyl-5-formyl-6-hydroxy-1,3-benzodioxol (yield=37.6%)in Fraction Nos. 1-3 as light yellow needle crystals.

[0221] Melting point: 104-105° C. TLC: Rf=0.68 (n-hexane/ethylacetate=2:1) ¹H-NMR (CDCl₃, δ ppm): 1.69 (s, 6H, Me₂), 6.37 (s, 1H,H-7), 6.76 (s, 1H, H-4), 9.60 (s, 1H, CHO) IR (KBr cm⁻¹): 3008, 1650,1614, 1494, 1422, 1394, 1388, 1382, 1340, 1282, 1248, 1182, 1156, 1068,984, 882, 844, 800, 782, 758, 704, 524, 470, 430

Assay Example 1

[0222] Assay for Antifungal Activity of Intermediates of EsculetinCompounds

[0223] (1) Compounds to be Tested

[0224] Antifungal activities of the following Compounds (a) to (e) wereexamined.

[0225] Compound (a): 2-benzyloxy-1,4-hydroquinone [the compound inSynthesis example 3(4)]

[0226] Compound (b): 2,5-dihydroxy-4-benzyloxybenzaldehyde [the compoundin Synthesis example 3(5)]

[0227] Compound (c): 2,5-diacetoxy-4-benzyloxybenzaldehyde [the compoundin Synthesis example 5]

[0228] Compound (d): 4,5-methylenedioxysalicylaldehyde [the compound inSynthesis example 6]

[0229] Compound (e): 2,2-dimethyl-5-formyl-6-hydroxy-1,3-benzodioxol[the compound in Synthesis example 7(3)]

[0230] (2) Pathogenic Fungi to be Tested

[0231] Antifungal activities against the following five plant pathogenicfungi were examined.

[0232] (i) Pyricularia oryzae(P.o in Table 1)

[0233] (ii) Fusarium nivale (F.niv in Table 1)

[0234] (iii) Septoria tritici(S.t in Table 1)

[0235] (iv) Pythium aphanidermatum (P.a in Table 1)

[0236] (v) Pytophthora infestans (P.i in Table 1)

[0237] (3) Procedures in Assay

[0238] Each of the test compounds (a) to (e) was dissolved indimethylformamide at the concentration of 1 mg/mL to prepare eachsolution for assay.

[0239] In Pyricularia oryzae (P.o) and Pythium aphanidermatum (P.a)among the above plant pathogenic fungi, distilled water (10 mL) wasadded to a petri dish in which spores were formed, and the concentrationof spores was adjusted to 1×10⁵ spores/mL. In Pytophthora infestans(P.i), distilled water (10 mL) was added to a petri dish in which sporeswere formed, and the concentration of spores was adjusted to 1×10⁴spores/mL.

[0240] In Fusarium nivale (F.niv) and Septoria tritici(S.t), a culturein a PDA medium (potato, dextrose, and agar medium) was carried outuntil the fungus was fully grown. The colony taken from one petri dishwas transferred with the medium to a vessel of a homogenizer. Sterilewater (50 mL) was added to the vessel, and the whole was dispersed bythe homogenizer at 5000 rpm for 30 seconds while cooling, and thenfiltered through two sheets of sterile gauze. After centrifugation (3000rpm, 5 minutes), a pellet was suspended in sterile water (50 mL)(1 to 3spores in a field of microscope at a magnification of ×100).

[0241] A suspension of spores or mycelia (10 mL) was added to a PDmedium (potato and dextrose medium) (90 mL), and stirred well. InPytophthora infestans (P.i), a rye liquid medium was used instead of thePD medium.

[0242] A flat-bottomed 96-well microplate was prepared. Each assaysolution (1 μL) was added to the microplate, and then each medium (100μL) containing an inoculum of each plant pathogenic fungus was furtheradded, and stirred well. In a control assay of a group without a drug(i.e., not containing a test compound), only dimethylformamide (1 μL)was added. Three wells per each test compound were used.

[0243] In a control assay in which no plant pathogenic fungus wasinoculated, an assay solution for control without inoculation wasprepared by adding sterile water (10 mL) to a non-inoculated medium (90mL), and the assay solution for control without inoculation (100 μL pera well of the microplate) was added.

[0244] A static culture was carried out at 20° C. or 25° C.

[0245] (4) Method for Evaluation and Results

[0246] The culture was carried out for a predetermined period (DAT)described in the following Table 1, and then OD₅₉₅ was measured using amicroplate reader. A rate of suppression was calculated in accordancewith the following equation (1):

[1−(T−R)/(C−R)]×100  (1)

[0247] wherein T is an absorbance (OD₅₉₅) in an assay group in which anassay solution containing a test compound was added to a mediumcontaining an inoculum of a plant pathogenic fungus; C is an absorbance(OD₅₉₅) in a non-drug group in which an assay solution without a testcompound was added to a medium containing an inoculum of a plantpathogenic fungus; and R is an absorbance (OD₅₉₅) in a non-inoculatedcontrol assay group in which an assay solution without a test compoundwas added to a medium without an inoculum of a plant pathogenic fungus.

[0248] The rate of suppression calculated as above was evaluated asthree grades in accordance with the following basis:

[0249] −: less than 10%

[0250] +: 10 to 60%

[0251] ++: more than 60%

[0252] The results are shown in Table 1. TABLE 1 Rate of growthsuppression (%) P.o F.niv S.t P.a P.i Test 3 DAT 4 DAT 7 DAT 1 DAT 4 DATcompound 10 mg/L 10 mg/L 10 mg/L 10 mg/L 10 mg/L Compound ++ + + + + (a)Compound + ++ + ++ + (b) Compound + ++ ++ + + (c) Compound + + + + + (d)Compound + + + + + (e)

Assay Example 2

[0253] Assay for Herbicidal Activity of Intermediates of EsculetinCompounds

[0254] (1) Compounds to be Tested

[0255] Herbicidal activities of the above Compounds (a), (b), (d), and(e) used in the above assay example for the antifungal activity wereexamined.

[0256] (2) Plants to be Tested

[0257] Effects of a germination suppression against the following fourplants were examined:

[0258] (i) Amaranthus retroflexuso (Amaranthaceae)

[0259] (ii) Lactuca sativa (Asteraceae)

[0260] (iii) Solanum nigrum (Solanaceae)

[0261] (iv) Setaria viridis (Poaceae)

[0262] (3) Procedures in Assay

[0263] Seeds of each test plant were treated with a 1% sodiumhypochlorite solution for 2 minutes, washed with sterile water, andair-dried, and then the assay was carried out using the resulting seeds.A filter paper (Kiriyama; for a funnel; diameter=21 mm) was placed on a12-well microplate, and seeds were seeded thereon.

[0264] Each test compound was dissolved in acetone at the concentrationof 10 mg/mL, and diluted with a 2-fold dilution of Murashige-Skoog salts(MS) to 200-fold. The prepared test compound solution (0.3 mL) was addedto the microplate, the edge thereof was covered with a cellophane tape,and the microplate was incubated in a temperature controlled room. In acontrol assay of a group without a drug (i.e., not containing a testcompound), only a diluted liquid (0.3 mL) prepared by diluting acetonewith a 2-fold dilution of Murashige-Skoog salts to 200-fold was added.

[0265] (4) Method for Examination

[0266] Growth at 25° C. under 4000 to 5000 1× (24 hours light condition)for 7 days was carried out, and then effects against Shoots and Rootswere evaluated by a visual assessment. The evaluation was carried out asthe following six grades:

[0267] 0: same as that without treatment

[0268] 1: suppressed by less than 20%

[0269] 2: suppressed by a range from 20% to less than 40%

[0270] 3: suppressed by a range from 40% to less than 60%

[0271] 4: suppressed by a range from 60% to less than 80%

[0272] 5: suppressed by 80% or more

[0273] The results are shown in Table 2. In Table 2, G is a germinationinhibition, Ig is a growth suppression, Ir is a growth suppression ofRoots, and Ur is negative geotropism. TABLE 2 Concen- Herbicidalactivity (0 to 5) Test tration Amaranthus Lactuca Solanum Setariacompound mg/L retroflexuso sativa nigrum viridis Acetone 5000  0 0 0 0Com- 50 5 G 4.8 G 5 G 1 IglrUr pound (a) Com- 50 5 G 0 5 G 3 GlglrUrpound (b) Com- 50 0 2 Ir 4 Iglr 0 pound (d) Com- 50 0 0 4 Iglr 0 pound(e)

Assay Example 3

[0274] Assay for Antifungal Activity of Esculetin Compounds

[0275] The activities of the following esculetin compounds was confirmedby a method similar to Assay example 1.

[0276] 7-benzyloxy-6-hydroxycoumarin [the compound in Example 3]

[0277] methylenedioxycoumarin [the compound in Example 6(1)]

[0278] esculetin acetonide [the compound in Example 7(1)]

Assay Example 4

[0279] Assay for Herbicidal Activity of Esculetin Compounds

[0280] The activities of the following esculetin compounds was confirmedby a method similar to Assay example 2.

[0281] 7-benzyloxy-6-hydroxycoumarin [the compound in Example 3]

[0282] methylenedioxycoumarin [the compound in Example 6(1)]

[0283] esculetin acetonide [the compound in Example 7(1)]

Preparative Example 1

[0284] Powder was prepared from the following composition. Parts byweight Compound (a) in Assay example 1  3 clay 40 talc 57

[0285] The above components were ground and mixed to prepare powder.

Preparative Example 2

[0286] Water dispesible powder was prepared from the followingcomposition. Parts by weight Compound (b) in Assay example 1 50 ligninsulfonate  5 alkyl sulfonate  3 diatomaceous earth 42

[0287] The above components were ground and mixed to prepare waterdispesible powder, which can be used by dilution with water.

Preparative Example 3

[0288] Granules were prepared from the following composition. Parts byweight Compound (c) in Assay example 1  5 bentonite 43 clay 45 ligninsulfonate  7

[0289] The above components were mixed uniformly, and water was furtheradded. The whole was kneaded and applied to an extrusion granulator toform a granular shape. Granules were obtained by drying.

Preparative Example 4

[0290] Emulsifiable concentrate was prepared from the followingcomposition. Parts by weight Compound (e) in Assay example 1 20polyoxyethylene alkyl aryl ether 10 polyoxyethylene sorbitan monolaurate 3 xylene 67

[0291] The above components were mixed uniformly and dissolved toprepare emulsifiable concentrate.

INDUSTRIAL APPLICABILITY

[0292] According to the present invention, the yield of the esculetinsynthesis is significantly improved in comparison with known methods.When one or more protecting groups are used, they can be removed easily.Therefore, the industrial value of the present invention is high.

[0293] Although the present invention has been described with referenceto specific embodiments, various changes and modifications obvious tothose skilled in the art are possible without departing from the scopeof the appended claims.

1. A process for manufacturing an esculetin compound of the generalformula (2):

wherein R¹ and R² are, independently, a hydrogen atom, an alkyl grouphaving 1 to 5 carbon atoms, an optionally substituted benzyl group, aformyl group, or an optionally substituted alkyl-carbonyl group in whichthe alkyl moiety has 1 to 4 carbon atoms; or R¹ and R² together form a—CH₂— group or a —C(CH₃)₂— group; characterized by cyclocondensing atrihydroxybenzaldehyde compound of the general formula (1):

wherein R¹ and R² have the same meanings as above; and R³ is a hydrogenatom, a formyl group, or an optionally substituted alkyl-carbonyl groupin which the alkyl moiety has 1 to 4 carbon atoms, in an aprotic polarsolvent in the presence of a weak base, with acetic anhydride or acompound which forms acetic anhydride in the reaction system.
 2. Aprocess for manufacturing a trihydroxybenzaldehyde compound of thegeneral formula (1):

wherein R¹ and R² are, independently, a hydrogen atom, an alkyl grouphaving 1 to 5 carbon atoms, an optionally substituted benzyl group, aformyl group, or an optionally substituted alkyl-carbonyl group in whichthe alkyl moiety has 1 to 4 carbon atoms, or R¹ and R² together form a—CH₂— group or a —C(CH₃)₂— group, and R³ is a hydrogen atom, a formylgroup, or an optionally substituted alkyl-carbonyl group in which thealkyl moiety has 1 to 4 carbon atoms, characterized by performing aformylation of a trihydroxybenzene compound of the general formula (3):

wherein R¹, R², and R³ have the same meanings as above.
 3. Atrihydroxybenzaldehyde compound of the general formula (10):

wherein R¹¹ and R¹² are, independently, a hydrogen atom or an alkylgroup having 2 to 5 carbon atoms, or R¹¹ and R¹² together form a—C(CH₃)₂— group, and R¹³ is a hydrogen atom, a formyl group, or anoptionally substituted alkyl-carbonyl group in which the alkyl moietyhas 1 to 4 carbon atoms, with the proviso that R¹¹ and R¹² are not ahydrogen atom at the same time.
 4. An esculetin compound of the generalformula (20):

wherein R²¹ and R²² are, independently, a hydrogen atom, an alkyl grouphaving 2 to 5 carbon atoms, an optionally substituted benzyl group, aformyl group, or an optionally substituted alkyl-carbonyl group in whichthe alkyl moiety has 1 to 4 carbon atoms, or R²¹ and R²² together form a—C(CH₃)₂— group, with the proviso that R²¹ and R²² are not a hydrogenatom at the same time, and that R²¹ and R²² are not a formyl group, oran optionally substituted alkyl-carbonyl group in which the alkyl moietyhas 1 to 4 carbon atoms at the same time.
 5. A trihydroxybenzenecompound of the general formula (30):

wherein R³¹ is an optionally substituted benzyl group, R³² is a hydrogenatom, a formyl group, or an optionally substituted alkyl-carbonyl groupin which the alkyl moiety has 1 to 4 carbon atoms, or R³¹ and R³²together form a —C(CH₃)₂— group; and R³³ is a hydrogen atom, a formylgroup, or an optionally substituted alkyl-carbonyl group, in which thealkyl moiety has 1 to 4 carbon atoms.
 6. An antifungal composition foragriculture and horticulture, characterized by comprising, as an activeingredient, a trihydroxybenzaldehyde compound of the general formula(10):

wherein R¹¹ and R¹² are, independently, a hydrogen atom or an alkylgroup having 2 to 5 carbon atoms, or R¹¹ and R¹² together form a—C(CH₃)₂— group, and R¹³ is a hydrogen atom, a formyl group, or anoptionally substituted alkyl-carbonyl group in which the alkyl moietyhas 1 to 4 carbon atoms, with the proviso that R¹¹ and R¹² are not ahydrogen atom at the same time.
 7. An antifungal composition foragriculture and horticulture, characterized by comprising, as an activeingredient, an esculetin compound of the general formula (20):

wherein R²¹ and R²² are, independently, a hydrogen atom, an alkyl grouphaving 2 to 5 carbon atoms, an optionally substituted benzyl group, aformyl group, or an optionally substituted alkyl-carbonyl group in whichthe alkyl moiety has 1 to 4 carbon atoms, or R²¹ and R²² together form a—C(CH₃)₂— group, with the proviso that R²¹ and R²² are not a hydrogenatom at the same time, and that R²¹ and R²² are not a formyl group, oran optionally substituted alkyl-carbonyl group in which the alkyl moietyhas 1 to 4 carbon atoms at the same time.
 8. An antifungal compositionfor agriculture and horticulture, characterized by comprising, as anactive ingredient, a trihydroxybenzene compound of the general formula(30):

wherein R³¹ is an optionally substituted benzyl group, R³² is a hydrogenatom, a formyl group, or an optionally substituted alkyl-carbonyl groupin which the alkyl moiety has 1 to 4 carbon atoms, or R³¹ and R³²together form a —C(CH₃)₂— group, and R³³ is a hydrogen atom, a formylgroup, or an optionally substituted alkyl-carbonyl group in which thealkyl moiety has 1 to 4 carbon atoms.
 9. A herbicide characterized bycomprising, as an active ingredient, a trihydroxybenzaldehyde compoundof the general formula (10):

wherein R¹¹ and R¹² are, independently, a hydrogen atom or an alkylgroup having 2 to 5 carbon atoms, or R¹¹ and R¹² together form a—C(CH₃)₂— group, and R¹³ is a hydrogen atom, a formyl group, or anoptionally substituted alkyl-carbonyl group in which the alkyl moietyhas 1 to 4 carbon atoms, with the proviso that R¹¹ and R¹² are not ahydrogen atom at the same time.
 10. A herbicide characterized bycomprising, as an active ingredient, an esculetin compound of thegeneral formula

wherein R²¹ and R²² are, independently, a hydrogen atom, an alkyl grouphaving 2 to 5 carbon atoms, an optionally substituted benzyl group, aformyl group, or an optionally substituted alkyl-carbonyl group in whichthe alkyl moiety has 1 to 4 carbon atoms, or R²¹ and R²² together form a—C(CH₃)₂— group, with the proviso that R²¹ and R²² are not a hydrogenatom at the same time, and that R²¹ and R²² are not a formyl group, oran optionally substituted alkyl-carbonyl group in which the alkyl moietyhas 1 to 4 carbon atoms at the same time.
 11. A herbicide characterizedby comprising, as an active ingredient, a trihydroxybenzene compound ofthe general formula (30):

wherein R³¹ is an optionally substituted benzyl group, R³² is a hydrogenatom, a formyl group, or an optionally substituted alkyl-carbonyl groupin which the alkyl moiety has 1 to 4 carbon atoms, or R³¹ and R³²together form a —C(CH₃)₂— group, and R³³ is a hydrogen atom, a formylgroup, or an optionally substituted alkyl-carbonyl group in which thealkyl moiety has 1 to 4 carbon atoms.